Thermal retarder mechanism



2 Sheets-Sheet l All l M. STERHELD THEQMAL RETARDER MECHANISM July 5, 194g.

Filed June 11, 1945 Judy 5, 1949. c. M. @STERHELD THERMAL RETARDER MECHANISM 2 Sheets-Sheet 2 Filed June ll, 1945 I V a" 1N l/'EN TOR.

Passed .my s, 1949 S yPATENT OFFICE THERMAL RETARDER MECHANISM Clark M. (Mlterheld,V Stoughton, Wis., assigner to McGraw Electric Com poration of Delaware pany, Elgin, Ill., a cor- Applicatlon June 1l, 1945, Serial No. 598,891

My invention relates to electric heating and particularly to control means for electric heaters for hot water tanks.

An object of my invention is to provide a control means for the electric heater of a hot water tank mounted in heat receiving relation on a tank and comprising a single switch, that shall cause closing of said switch in case the control means is subject to cold water in the tank and that shall cause opening oi said switch in case the control means is subject to hot water in the tank.

Another object of my invention is to provide a control system for the electric heater of a hot water tank that shall be energized. immediately at the beginning of an .0H-peak period in case the tank contains a substantial quantity of cold. Water and that shall delay energization ci the electric heater for a predetermined time period of delay in case the tank contains a relatively small quantity of cold water.

Another object oi' my invention is to provide a thermal retarder for use in a water heater control system embodying a rst snap-acting bimetal bar assembly adapted to move a contact member into circuit opening position under certain conditions and a second creep type bimetal bar adapted to move said contact member into circuit-closing position against the tendency of said bimetal bar assembly to keep it in circuitopening position.

Other objects of my invention will either be apparent from a description of several forms of device embodying my invention or will be pointed out in the course of such description and set forth more particularly in the appended claims.

In the drawings,

Figure 1 is a vertical, sectional view oi a hot water tank and a diagram of connections of an electric circuit,

Fig. 2 is a horizontal, sectional view taken on the line 2-2 of Fig. 3,

Fig. .3 is a vertical, sectional view of one iorm of thermal retarder embodying my invention,

Fig. 4 is'a horizontal, sectional view taken on theline I-I of Fig. 3,

Fig. 5 is a horizontal, sectional view taken on the line 5-5 oi F1g.;6, u

Fig. 6 is a vertical, sectional line 6-6 of Fig. 5,

Fig. 'I is a horizontal, sectional view of a modivview taken on the iled form of the retarder taken on the line 1-1- of Fig. 8, and,

Fig. 8 is a vertical, sectlonalview 8 Claims. (Cl. 219-39) Referring rst of all to Fig., 1 of the drawings, I have there shown an ordinary domestic hot water tank l l having a lower cold water inlet pipe I3 as well as an upper hot water outlet pipe l5 secured thereto. The tank Il may be covered with heat insulation Il which heat insulation is held in proper operative position around the tank Il by an outer casing i9.

I provide also preferably, but not necessarily, a Single electric heater 2i and if only a-single electric heater is provided, l prefer tc position it adjacent the lower end of the tank it and may locate the heater 2l in a tunnel member 23, all in a manner now well known in the art.

I provide also a lower heater control switch designated generally by numeral 25 which switch includes a bimetal bar 2l having its lower end mounted on a fixed contact 2t while its upper ends adapted to engage with and he disengaged from a contact 3 l. While I have shown a specific embodiment of a heater control switch 25, I do not desire to be limited thereto but may use any form of control switch which will have the same operation as the switch 25. Switch 25 is designed, constructed and adjusted to close its circuit when it is subject to cold water in the tank and to remain closed until the water to which it is subject reaches a temperature on the order of, say to 140 F. When the temperature of the water to which bimetal bar 21 is subject reaches, say F., the bimetal bar will move so that its upper end is out of engagement with xed contact 3| substantially as shown by the dashed lines shown in Fig. 1 of the drawings.

Referring now to Figs. 2, 3, and 4, I have there shown one form of device embodying my invention. A block 33 which is preferably made of a metal or alloy having high heat conductivity has an inner surface which has substantially the same contour as the outer-contour of tank ll and which may be held in proper operative position against the outside surface of tank ll as by welding seams'35. f

Bolted against the front flat surface of support 33 is a supporting member 31, of heat-conducting material, which is of substantially L-shape in vertical section having a lower thickened and peculiarly shaped portion 39 which is adapted to be secured against support 33 by a plurality of short-machine screws 4I. Portion 39 has an angularly extending front surface having a recess therein and adapted to have secured thereagainst one end portion of a bimetal toggle arm 43 as by at least one short-machine screw 45.

55 The upper movable end of bimetal bar 43 has a may be solidly brazed or welded against the outer or upper ends of bimetal bar 43. I provide a second toggle arm 49 which is provided in its lower portion with a longitudinally extending recess and I provide further an over-center spring having its upper end pivotally connected to the arm 49 just beyond the end ofthe recess. The upper end portion of bimetal bar 43 is also provided with a median longitudinally extending recess to receive the lower end portion of spring 5|. The two side pieces of the upper toggle arm 49 are sharpened and are adapted to extend into recesses provided in the pivot plates 41. The design and construction of members 43, 41, 4 9 and 5| is such that the outer or upper end of the second toggle arm 49 will move with a snap action when subject to predetermined changes of `temperature.

I provide a contact bridging member 53 which is secured against the outer surface of a support 55 of electric-insulating material which is loosely pivotally mounted on'the outer end of the second toggle arm 49.

I provide a casing 51 of electricand heatinsulating material having its lower end portion secured in proper operative position against the lower horizontally extending portion of member 31 by a plurality of machine screws 59. On the back wall of casing 51, I mount a pair of fixed contacts 9|, which are adapted to be engaged with and disengaged from the contact bridging member 53, and which are connected as shown in Fig. 1.

Contact bridging member53 will be in engagement with contacts 5| when bimetal bar 43 is subject to cold water as hereinbefore'described and will be out of engagement with contacts 5| when subject to hot water in the tank.

I provide also a time controlled switch comprising contact arms 53 and 65 which are adapted to be in conducting engagement with each other duringoiI-peak periods and which are adapted to be out of engagement with each other during on-peak periods. I may use any type of continuously operative timer to effect the above mentioned engagement and disengagement. I provide a pair of supply circuit conductors 91 and 39 of which conductor 61 may be connected to contact arm 63 while contact arm 55 is connected to one of the iixed contacts 6| by a conductor 1|. The other iixed contact 6| is connected by a conductor 13 with one terminal of heater coil 2|, the other terminal of which is connected to xed contact 29 of the lower control switch 25. Fixed contact 3| is connected by a conductor 15 with the second supply circuit conductor 69. Since it is desired to eiiect energization of heater 2| immediately upon closure of the time f controlled switch comprising contact arms 63 l and 65 in case sufficient cold water is in tank Referring particularly to Fig. 3 of the drawings, I have there shown a creep type bimetal bar 11 having its lower end fixedly secured against a front surface of member 51 as by screws 19, which bimetal bar'has a relatively small, low

wattage heating coil 9| insulatedly mounted theron.

The upper end of bimetal bar 11 has a relatively small opening therethrough, through which opening there extends a rod 93 having two adjustable nuts l5 and I1 mounted thereon on screw threads. The inner end of rod 93 is pivotally connected with the junction of two toggle arms 99 and 9|, toggle arm 99 being pivotally supported on a stub shaft 93 supported by a projecting lug 95 xed against the upperV surface of the vertically extending portion of member 31. Over-center spring 91 is connected at its upper end to the stub shaft 93 hereinbefore mentioned and has its lower end connected to a stub shaft or pin 99 which extends into the lower arm 9| intermediate its ends. Normally the togsles 99 and 9| will be in the position shown in full lines in Fig. 3.

One terminal of heating coil 3| is connected by a conductor |0| to conductor 1| while the other terminal of heater coil is connected by a conductor |03 to the fixed contact 29 of switch 25.

Let it now be assumed that the two contact arms 63 and 95 are moved into contact with each other at the start of an off-peak period, which for convenience, may be set at 11:00 p. m. In case bimetal bar 43 is subject to cold water in the tank, it will be in such position 'that contact bridging member 53 is in engagement with fixed contracts 6| whereby an energizing circuit through heater 2| is closed, this circuit being substantially as follows: from supply circuit conductor 01, through the engaged contact arms 53 and 65, conductor 1|. through the contact bridging member 53, contacts 6|, conductor 13, heater 2|, through the closed switch 25 and from there through conductor 15 to the other supply circuit conductor 59. This will therefore energize heater 2| and this energization will continue until suicient water in the tank has been heated to a temperature on the order of F., the level ofhot water gradually creeping downwardly until bimetalbar 43 is subject to hot water in the tank and will move the contact bridging member 53 into open position substantially as shown by the dashed lines in Fig. 3 of i the drawings, whereby the heater is deenergized,

and the second toggle arm 49 will bev l moved against a lug |04 yon the lower end of toggle arm 9|.

Simultaneously with the energization of heater 2| the low wattage coil 9| is also energized and the design, construction and adjustment of heating coil 9| is such that the temperature of bi- 53 will be moved into engagement with fixed contacts 0I whereby the hereinbefore described energizing circuit through heater coil 2| is again closed. The eiect of the flexing of bimetal bar 11 in a counter-clockwise direction is that the lower end of toggle arm 9| is moved in a counterclockwise direction and the upper end portion o1' toggle arm 49 is moved in a clockwise direction, so that contact bridging member 59 is moved into engagement with fixed contacts 9| substantiallyashereinbefore described. It may be here lpointed out that the bimetal ybar 43 will maintain.'

5. itself in substantially the position shown by the broken lines in Fig. 3.

Energization of heater' 2| will continue until either one or two results occur; if substantially all ofthe water in the tank is heated to a temperature of 150 before the opening of the time controlled switch, deenergization of heater 2| will be eifected by the thermal switch 25 while if less than all of the water in the tank is hot at the time of termination of an off-peak period. which we may assume to be at 6:00 a. m., deenergization of heater 2| is effected by the time controlled contact arms 63 and 65.

Thehereinbefore described thermal retarder .casing 51 may be provided with a front closing wall and a cover |01 may also be provided. An outer cover |08 may also be provided on member 31.

Referring now to Figs. 5 and 6 of the drawings, I have there shown a modiiication particularly of the second bimeta1 bar means. Referring more particularly to Fig. 6 vof the drawings, I- have there shown that the fixed contacts 6| may be supported by a block of electric-insulating material |09 which is supported by a bracket III. The second-bimetal bar 11 is adapted to be loosely pivotally connected with a push rod ||3 which extends outwardly through the rear wall of casing 51 through an opening ||5 therein and which may have a pivot plate ||1 secured thereagainst,

the outer rounded end portion of pivot plate I1 being adapted toengage against the upper end portion of bimetal bar 43 upon flexure of bimetal bar 11 in a counter-clockwise direction suflicient to cause reengagement of contact bridaing member 53 with fixed contacts 6| in substantially the same manner and with or without a time delay period as was hereinbefore set forth in connection with the design shown in Figs. 2, 3 and 4.

Referring now to Figs. '1 and 8 of the drawings, I have there shown a still further modication of a'device embodying my invention and comprising a bimetal toggle arm |2|, the upper end of which is secured as by a machine screw |23 against a part of the front surface of a casing |25 of heat-conducting material which is adapted to be secured by means not shown against the front surface of support 33. A second toggle arm |21 is provided with pivot plates 41 and an overcenter spring 5| may also be provided connected to toggle arms |2| and |21 as hereinbei'ore de scribed. A contact bridging member 53 is adapted to engage with and be disengaged from a pair of iixed contacts 6| mounted onl a block |23, of electric-insulating material, against an upstanding lug |3| on the inner upper surface of casing |25, as by machine screws |33. A second bimeta1 bar |35 is of substantially spiral form, having one of its ends flxedly supported as by a pin |31 projecting into a sup porting block |39 which may be made of heatinsulating material. The other end of the spiral bimetal bar |35 has secured thereto an arm |4I, the outer end. of whichfits loosely into a recess in a short rod |43 which rod is adapted to be moved in a left-hand direction upon increase of temperature of the bimeta1 bar |35. Increase of temperature of the bimetal bar |35 is effected by a low wattage heating. coil |45, the design, construction and adjustment of which is such that bimetal bar |35 will be caused to increase in temperature to a value sufficient to have the lefthand end of rod |43 engage the lower end of bimetal toggle arm |2| and cause reengagement of which is .secured moved to the position shown by the broken Alines in Fig. 8, under the conditions hereinbefore de scribed.

Substantially the same` comments made hereinbefore in connection with the design shown in Figs. 2, 3 and 4 apply equally well to the designs shown respectively in Figs. 5 and 6 and in Figs. 7 and 8 and repetition thereof is believed to be unnecessary.

It is evident that the second or creep type bi metal bar is effective tovcause reclosure of the heater controlled circuit either with or without a time delay depending upon the amount of cold water in the tank at the start of an off-peak period, against the tendency of the bimetal toggle arm to maintain the contact bridging member in its circuit opening position.

Various modifications may be made in the device embodying my vinvention without departing from the spirit and scope thereof and all such modifications clearly coming within the scope of the appended claims shall be considered a part of my invention.

I claim as my invention: I

l. A thermal retarder comprising a snap-acting bimetal bar assembly, a contact bridging member adapted to be moved into circuit-closing position when the temperatureI of said bimetal bar assembly is low and to be moved into circuitopening position when the temperature of said bimetal bar assembly is high and means comprising a creep type bimeta1 member and an electric heating coil for heating said creep type bimeta1 member for causing movement of said contact a predetermined period of time after energization of said heating coil.

2. A thermal retarder comprising a snap-acting bimetal bar assembly, a contact member carried by said assembly and adapted to be moved into circuit-closing positionl when the temperature of said assembly is lowl and to be moved into circuit-opening position when the temperature of said assembly is high and means comprising a thermally-actuable member and an electric heating coil for heating said thermally-actuable member for causing movement of said contact member, when in circuit-opening position, into circuit-closing position a predetermined period of time after energization of said electric heating coil.

3. A thermal retarder for controlling the energization of an electric heater for a. hot water tank, adapted to be mounted in heat-receiving relation on a hot water tank, comprising a, snapacting bimetal bar assembly, a contact member carried by said assembly adapted to be moved thereby into circuit-closing position when subject to cold water in the tank and to be moved thereby into circuit-opening position when subject to hot water in the tank and means comprising a thermally-actuable member and an electric heating coil operatively associated with said thermally-actuable member for heating said member to cause movement of said contact member, ywhen in circuit-opening position, into circuit-closing position a predetermined period of timle after energization of said electric heating coi.

4. A thermal retarder comprising a snap-acting toggle joint assembly, one of said toggle arms being of bimetal, a contact member carried by said assembly and adapted to be movedinto circuit-closing position when the temperature of said assembly is low and to be moved into circuitopening position when the temperature of said assembly is high and means comprising a creep type bimetal bar, said snap-acting. toggle joint assembly being normally in position so that said contact member can move freely into circuitopening position and adapted to be actuated by said creep type bimetal bar and an electric heating coil insulatedly mounted onv and supported by said creep type bimetal bar lfor causing movement of said contact member into circuit-closing position a predetermined length of time after energization of said heating coil. ,Y

5. A thermal retarder for controlling the cnergization of an electric heater for a hot water tank, adapted to be mounted in heat-receiving relation on a hot water tank, comprising a snapacting toggle joint assembly, one of said toggle arms being of bimetal, a contact member carried by said assembly vadapted to be moved thereby into circuit-closing position when subject to cold water in the tank and to be moved thereby into circuit-opening position when subject to hot water in the tank and means comprising a creep type bimetal bar, said snap-acting toggle joint assembly being normally in position so that said contact member can move freely into circuit-opening position and adapted to be actuated by said creep type bimetal bar and an electric heating element insulatedly mounted on and supported by said creep type bimetal bar, for causing movement of said contact member into circuit-closing position a predetermined length of time after energization of said heating coil.

6. In combination, a movable, circuit-controlling. electric contact, stops for limiting the movement ofsaid contact, at least one of said stops constituting a cooperating, circuit-controlling contact, a snap mechanism for moving said movable contact between said stops, and a thermally actuated snap mechanism for moving one of said stops.

7. In combination, a movable, circuit-controlling, electric contact, stops for limiting the movement of said contact, one of said stops being movable, the other constituting a cooperating electric contact, a thermally-actuated snap mechanism for moving said movable contact between said stops, and a second thermally-actuated, snap mechanism for moving said movable stop toward and away from the other stop.

8. In combination, an electric switch including a contact operating member and a stop therefor, first thermally actuated means for moving said contact operating member between said stop and a circuit-closing position, a snap mechanism for moving said stop for pushing said contact operating member into said circuit-closing position, and second thermally actuated means for operating said snap mechanism.

CLARK M. OS'I'ERHELD.

REFERENCES CITED The following referenloes are of record in the tile of this patent:

UNITED STATES PATENTS Number Name Date 2,175,827 Conklin Oct. 10, 1939 2,210,084 Kuhn et a1 Aug. 6, 1940 2,257,887 sterheld Oct. 7, 1941 

